Modern casting practice has tended toward lighter weight castings utilizing less metal and capable of withstanding higher stresses. This means that higher tolerance casting procedures must be employed. Furthermore, to improve productivity, a paramount consideration today, procedures must be taken to reduce the amount of scrapage and visual inspection labor that is required in present day foundry practices. There is no sense pouring metal, for example, into a mold that is no good, only to scrap the casting later.
In addition to that problem, if one is capable of producing scrap, one must also inspect for this. Inspection costs a lot of money and what is worse is many visual inspection procedures miss the problem which then gets out into the field and becomes a warranty and customer satisfaction problem of the first order.